This invention relates to wall structures and to structural elements usable in the wall structure.
Frame-and-panel wall systems have been used for some time, both for filling and closing openings in building walls ("store front" applications) and for enclosing building structural frames ("curtain wall" applications). Modern systems typically employ extruded aluminum shapes for the frame members, and glass, plastic or metal panels. The shapes employed to form the frame members, whether single piece or multi-piece, are often made quite complex in an effort to meet all of the installation and functional requirements of an effective frame member. Such requirements include adequate structural strength for the static and dynamic loads to be encountered, weather-tight gripping of the panels, water-tightness, ease of erection of the frame and installation of the panels therein (or at least a basic feasibility of such operations), ease of reglazing, and adaptability to widely varying installation situtations. One desirable feature of wall frame members employed in cold climates is that of thermal insulation, but this feature has been difficult to provide in view of the excellent thermal conductivity of aluminum.
The increasing complexity of the frame-forming shapes in panel wall systems has led to a multiplication in the number of pieces involved in a given system, including, for example, different pieces which have the same basic structure, but are "right-handed" or "left-handed" to fit in particular sections of an installation. The increased number of parts complicates manufacturing operations, warehousing at all distribution levels, ordering, job planning and layout, and the installation work itself.